Light or Darkness
by Blackdemon21
Summary: The sun shone high in the sky over the happy family as they walked through heaven, the border dividing heaven and hell close beside, but little did they know of the danger approaching. Sebaciel, AU, OOC.
1. Chapter 1

**Prologue**

 **A/N: Hey my little yaoi kittens, I'm back with another angel and demon fanfiction. This story may be different from my last story that delt with this type of AU, well that's all I had to say and I guess I'll see you all in the next authors note.**

 **Summary:** **The sun shone high in the sky over the happy family as they walked through heaven, the border dividing heaven and hell close beside, but little did they know was the danger approaching.**

 **Disclaimer: I don't own anything**

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Two angels, one with hair as golden as the sun and eyes blue as sapphires and the other with hair a dark midnight blue with chocolate brown, cared for their year old son who had hair like his father and eyes like his mother. The sun shone high in the sky over the happy family as they walked through heaven, the border dividing heaven and hell close beside, but little did they know was the danger approaching that would break the barrier.

The cherubs father was a very strong archangel who fought off demons that managed to cross. His mother was a healer who took care of injuries that the warriors that came back from fighting.

The brown eyed angel kept a hand on the hilt of his blade that was strapped to his hip as he heard the imps that strayed close to the borders edge began to giggle amongst themselves. Whatever they were planning had every angel that was patrolling on edge and ready to strike at any moment, but none of them were prepared for the earth quaking screech that came from the dark clouds that covered both sides.

The sun that shone beautifully was now shrouded in darkness, as a snake like figure flew through the clouds. Both Angels and Demons knew what this creature was and ran to protect the children while the archangels, warriors, and archers prepared for battle. A light green-serpent-like-dragon with large leathery wings flew down toward the barrier, destroying it easily. This creature was a leviathan, a dragon that was able to harness the power of lightning and could only think of destruction.

The golden haired angel held her son close as the imps and demons charged across the border, attacking and stealing everything they could get their claws on. The cherubs mother ran as fast as she could until she found herself tripping, losing her grip on her child that began to cry as an imp sniffed at the infant, picking it up in its clawed hands and running off as his mother cried out for her child to be returned.

The imp ran across the border carrying the crying child in its arms. It ran far from the battle raging at the border, until it came to territory of a strong demon that everyone in hell knows not to bother.

This demon usually stayed in its home, a cave on the side of a mountain that held its nest, but the slightest sound of something in its territory always woke it, and it was never happy.

The giggling imp stopped and set the child on the hot ground and bared its fangs, ready to kill the child when the sound of wing flaps and an angry voice caught its attention. It turned around when a tall dark shadow loomed over it and it was met with a pair of glowing red eyes, both narrowed in anger as two large black wings arched over the demon like a halo.

"What do you think you're doing in _my_ territory?" He asked, emphasizing the "my" in his question. The imp quivered in fear, it's thin tail going between its legs like a frightened dog,"I-I apologize, I didn't...I didn't realize this was your territory,"the frightened imp said. "You should be grateful that I wouldn't feed your disgusting hyde to my ravens," just as the demon said "ravens" a large bird with jet black feathers, glowing red eyes, and razor sharp talons landed on the demons shoulder, cawing at the imp to reveal rows of sharp fangs.

With a threatening snarl, the imp ran off, leaving the cherub. The infant was still crying and the demons mouth turned up into a grimace as he leaned down and carefully picked up the child. "What would that imp be doing with an angel?" He asked.

The raven perched on his shoulder looked at the child in his arms curiously, then jerked back when the child began to stop crying and reached out to touch the black feathers of the demons pet.

The man couldn't help but think this child was cute, even if he was an angel as he held out a clawed finger toward the infant and watched as the child giggled and grabbed the finger within its tiny hands, melting the demons heart as he smiled at the cherub and held him close. His nurturing instincts began to take over and he said,"you may be an angel but I wouldn't mind raising you to become a demon."

The red eyed male opened his jet black wings and and carried the child back to his home. The cavern was lit by crystals only found in hell, but they don't shine so bright that they would keep the demon up when he was resting. In the center of the cavern was a nest made of dead branches and leaves, but he covered it in blankets and pillows so it would be comfortable both for him and this child.

He shushed the child as he laid the cherub on the mound of pillows and carefully laid next to the cherub, covering the baby with a wing. The demon glanced at the child sleeping beside him one last time and smiled as he closed his eyes as his black snake like tail curled around the child protectively.

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 **A/N: Well everyone, that was the first chapter of the story, sorry if it's so short but this is a prologue after all. Well that's all I had to say and I guess I'll see you all in the next chapter, Ciao.**


	2. Chapter 2

**Chapter 1**

 **A/N: Hey my little yaoi kittens, I'm back with the chapter of my newest story. I've decided to write this in third person rather than first because I grown used to writing in explicit detail. There's also going to be multiple time skips in each chapter to show Sebastian and Ciel's life together. Anyways, that's all I had to say and I'll see you all in the next authors note.**

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Its been about a week since that red eyed demon took in the young cherub. At the moment, the demon was sleeping until a sound woke him up. The baby had started crying.

Sebastian sat up and picked up the child, wrapping him in a blanket as he shushed him hoping to lull him back to sleep. "What's wrong little one? You can't be cold, so what-" the demon was interrupted mid-sentence when he heard a dull rumble come from the child's stomach. He was hungry.

There was no way he could feed the child unless he had milk from an angel. Both demons and angels were raised and feed differently, new born demons would nurse on the blood of their caretaker, while angel seemed to act more like humans and feed off breast milk from their mothers.

"If I can't feed you like an angel, I'll do the only other option," the red eyed make bit his thumb, allowing blood to well up as he sheathed his claws and put his thumb in the child's mouth, only to see him whine and try to move away while the demon held him still.

"I know it doesn't taste that good, but you'll get used to it over time," the demon said. The little angels whines stopped then he wrapped his hands around the demons finger, nursing on the blood being fed to him. "That's a good boy-now, I need to name you, what could be a good name for you?"

The infant released his thumb and yawned, his eyes opening and clowns from time to time as he drifted off to sleep once again. "Hm, I think Ciel would be a good name for a little cherub-" The red eyed male paused mid-sentence and noticed the tuffs of feathers on the child's back were now a dull shade of gray. "Actually, calling you a little demon would suit you much better," the demon said with a chuckle as he laid the sleeping child down again and laid next to him, staying awake to make sure nothing happened.

 **(Timeskip)**

A child who appeared to be no older than ten years old with dull-grey-wings, sapphire blue eyes, and navy blue hair sat and waited for his guardian to come home while he played with a couple ravens that were perched on a few dead trees that stuck out from the mountain.

The young boy wandered a little too far to the edge of the side of the mountain where his home resided and the ledge gave way, causing him to fall. His wings weren't big enough for him to fly yet so all he could do was cry out for help.

His falling was stopped mid fall. He slowly opened his eyes, that he shut tightly, and they widened as he smiled and said,"Sebastian!" Ciel wrapped his arms around the demon and nuzzled into the crook of his neck. "Ciel, what happened?" Sebastian asked, flying up to the ledge and carrying Ciel into the cavern. "I had gone outside and the ledge gave way. I-I was so scared," Ciel whimpered as Sebastian rubbed the child's back, saying,"it's okay Ciel, I'm here, I won't let anything happen to you."

"Now, I bet you're hungry, right?" Sebastian asked as he sat on his knees so he was at the same height as Ciel. "Yeah," Ciel said, waiting for Sebastian to feed him like he always did, but this time, it was different since Ciel was older. "Well, since you're older I've decided that you've become old enough to stop nursing on blood and you can start eating meat like most demons your age," Sebastian said as he held out a raw piece of meat that was still dripping blood.

"It may not taste that good at first but you'll like it after eating for a few days," Ciel was hesitant as he took the meat from Sebastian and sniffed it curiously to know that it smelled edible. He opened his mouth and bit down, using his canines to tear at the meat. "How does it taste?" Sebastian asked, not knowing how the boy would react. "It tastes amazing!" Ciel said happily; Sebastian couldn't help but chuckle as he pet the boys head and looked to see the boys once pure white feathers slowly turned a shade darker.

 **(Another Timeskip)**

"Come on Ciel, just flap your wings a little harder," Sebastian had taken the boy out of the cavern for the first time in years as he tried to teach the boy how to fly now that his wings were fully grown. Ciel appeared be in his teens in human years but his height would make people think he was much younger.

No matter how hard he tried, Ciel couldn't get himself off the ground. "Hm...it appears this isn't working, so let's try something else," Sebastian said as he grabbed Ciel's wrist and flew into the air. "Ciel, I want you to keep flapping your wings okay, but don't move them so frantically," the blue eyed boy nodded and Sebastian released his wrist, shocking the boy as he did as Sebastian told him, hoping it would work and he found himself slowing down until he stopped.

"Well done Ciel, I knew you'd be able to do it," Sebastian praised the boy as Ciel flew over and hugged him, his mouth curling up into a smile as he said," I love you, Sebastian." This shocked the red eyed male to a great extent; he did care for the child like a son but it was difficult for him to say it, but if it was true he couldn't lie.

"I love you too, Ciel."

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 **A/N: Well everyone, that was the next chapter of this story, sorry if this chapter is terribly written, but I just wanted to explain how Sebastian raised Ciel through different moment through his life. Well, that's all I had to say and I guess I'll see you all in the next chapter, Ciao.**


	3. Chapter 3

**Chapter 2**

 **A/N: Hey my little yaoi kittens, I'm back with the next chapter of my story. This chapter is where I begin the plot of the story because the last chapter was just talking the angel and demons life together. Well that's all I had to say and I guess I'll see you all in the next authors note.**

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Sebastian slept in his nest, his wings folded to his back and his tail curled around himself as his chest moved up and down slowly, but within the furthest regions of the cavern, a pair of eyes watched the sleeping demon. The figure let out a low growl and stalked over to him on all fours as their mouth curled up into a grin and he lunged at the sleeping demon, only for a thin-black-tail to wrap around their waist and sit them on the floor as Sebastian sat up and smirked at the person who had tried to pounce on him.

"Ciel, you know you can't attack me that easily," Sebastian said, smirking at the child who sat in front of him, pouting with his arms crossed. "Oh, don't be like that. Why don't you go hunting and let me finish sleeping," Sebastian yawned, as he closed his eyes and fell asleep. Ciel always wondered why the elder slept more than the average demon, but he'd ask once he got back.

Ciel opened his wings and floated to the ground, walking to the torture pits where most demons hunted. It would take a couple minutes when it came to flying, but Ciel always preferred to walk and watch the Angels across the border. He grimaced at the sight of them as the higher ranking, or archangels as Sebastian called them, patrolled the line. Each one wielding sword that could slay a demon with one slice.

"Hey Ciel!"

The blue eyed boy flinched at the sound of the voice and looked up to see and incubus with short blonde hair and sky blue eyes land beside him. "Hey Alois, shouldn't you be with Claude?" Ciel stated. He had been introduced to these two when Sebastian had taken the boy to see the border for the first time.

"Claude is dealing with the new recruits. Where's Sebastian?" Alois asked, his hands behind his back as he walked beside the blue haired boy,"he sleeping like always. Do you or Claude know why he does that so much? Demons don't need sleep," Ciel stated; Alois shrugged his shoulders,"I don't know, Claude says it's because he's the general of kings army and he has nothing to do."

"I think it's because he's lazy," Ciel said causing both of them to laugh, but it was cut short by a loud voice. Both boys turned their heads and saw what appeared to be an angel of higher ranking talking to the warriors standing guard. "I couldn't stand being an angel, there's too many rules you'd have to follow," Alois said with a roll of his eyes. "Yeah, there's also the fact that they kill millions of demons," Ciel said as he glared at them.

"That's something I agree with as well. Anyways, where are you heading to?" Alois said, changing the subject. "Sebastian sent me to collect a few souls from the torture pits," Ciel said,"I was heading there as well," Alois said as he draped an arm over his friends shoulder and smiled.

In the distance, the sound of pained screams in agony gradually grew louder as the two boys noticed the ground starting to crack and imps began to appear. The two finally reached the torture pits, a crack going through the earth that was filled with fire and the tortured cries of souls, as creatures that flew over began to drop new souls in, only to be caught and eaten by some of the imps.

Both Ciel and Alois caught a good amount of souls before the imps could pick them off. Alois held a blue wispy orb over his mouth and swallowed it whole, licking his lips as he held another in his other hand. Ciel swallowed one of the souls he caught, tasting that it was sweet. "Thanks for coming with me Alois, but I'm going to head home now before Sebastian worries," Ciel said, waving to the incubus. "Okay then, see you later Ciel," Alois said.

Ciel began walking back home, stopping to bother some of the imps from time to time and laughing when they scattered like ants. He was getting close since he could see it in the distance, but he was stopped by a young female voice.

"Excuse me, may I ask what you are doing over there? It's dangerous."

Ciel turned his head to the sound of the voice and the person gasped at the sight of Ciel's appearance. The more Ciel was raised by Sebastian, the darker his wings became and his appearance changed as well; his left eye was blood red while the right was still a beautiful shade of sapphire, his canines had grown sharper, and his nails were a dark grey.

"What are you talking about? This is my home, or have the angels started to become a little absent minded," Ciel said with a smirk as he approached the border to see a girl with long blonde hair in pigtails, emerald eyes, with pure white wings, and wearing a white dress that went down to her feet. "U-Uh, you're wings may be a little corrupted but you're not supposed to be in hell," she said with a stutter in her voice.

"I'm a demon, so how can this not be my home?" The multi-color eyed boy asked. "You're no demon. You're an angel, it's obvious that those demons have been lying to you if-" "Shut the hell up you filthy angel! There's no way that I'm being lied to by the ones who raised me when I was only an infant, now leave me alone you annoying girl," Ciel spat as he turned away, ignoring the girl who could only think over what Ciel had said.

Ciel opened his dark grey wings and flew up toward his home, and entered the cavern to be greeted by Sebastian. "Welcome back Ciel, did anything interesting happen?" The red eyed male asked as feed one of his many ravens. "I met up with Alois while I was on my way to the pits and on my way back some angel tried to tell me that I wasn't a demon. She said I was corrupted."

Sebastian's eyes widened at this,"you didn't believe them, did you Ciel?" Sebastian asked as put a hand on the boys shoulder. "I didn't. I know everything they say is a lie," Ciel said; Sebastian's eyes softened when he heard those words and gently caressed the boys cheek. "Good boy. Those filthy creatures only tell lies, and I've taught you that you can't trust them no matter what they say, right?" Ciel nodded and said," yes Sebastian."

"Good, as long as you know this, no one shall ever hurt you or steal you away from me," the red eyed male held boy close, protectively. He'd never allow anyone to take what belonged to him, and if they did, they'd meet a fate worse than death.

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 **A/N: Well everyone, that was the next chapter of the story, if anyone is confused about the color of Ciel's wings, they're still a light grey, almost the color of cobblestone. Well, that's all I had to say and I'll see you in the next chapter, Ciao.**


	4. Chapter 4

**Chapter 3**

 **A/N: Hey my little yaoi kittens, I'm back with the next chapter of my story, in this chapter something that's very vital to the plot is about to happen. Anyways, that's all I had to say and I guess I'll see you all in the next authors note.**

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It would be considered morning in hell at the moment, but no one could tell, especially when the only thing lighting the place were wandering souls and the flames of hell. Sebastian was still sleeping while Ciel stayed on the ground, chasing imps and catching them by their tails then releasing them, laughing as they tripped over their own feet and ran into each other until they tired themselves out.

"Hahaha! Now I see why you're the lowest leveled cre To atures in hell," Ciel said as he picked up one of the tiny demons by its tail and held it up to his face growled, watching as the weak demon let out a startled shriek and curled up into a ball as Ciel dropped it while bursting into a fit of laughter while the demon ran off.

Ciel had to wipe a tear from his eye from how hard he was laughing until it died down and he stopped, nudging the little creatures with a pale finger. A tall winged shadow soon loomed over him not a second later and the young demon could sense that whoever this shadow was, was definitely not an ally. Ciel looked behind him and his eyes widened at what he saw. It was an angel.

Ciel was ready to open his wings and fly away, when the angel wrapped both of his arms around the child's waist and began carrying him to the border as Ciel cried out,"Let me go! Let me go! If you don't Sebastian will kill your white winged ass!"

"That's right, now if I were you I'd release him before I tear those pretty little wings off your back."

The archangel froze as Sebastian appeared in front of him, snarling and baring his fangs, causing the angel to jump back in shock. "I will not allow you to corrupt this angel anymore demon!" The angel shouted as he unsheathed his sword and pointed it at the demon who responded with a roll of his eyes.

This caused anger to run through the angels veins as he charged at the demon, ready to run him through when Sebastian easily caught the archangels wrist in his hand and slowly began to tighten his grip until the angel dropped the sword, groaning in pain through clenched teeth. Sebastian continued to tighten his grasp until he heard the wrist brake beneath his grasp and the man started crying out for mercy and released Ciel.

"If you ever try to take Ciel again, you won't be so lucky to walk away with just a broken wrist. Now, leave before I change my mind," Sebastian said with growl. The angel nodded frantically and scrambled to his feet, flying off.

Sebastian turned to Ciel, crouching down and caressing his cheeks. "Are you okay Ciel? Did that angel hurt you?" He asked in a panicked tone, when he saw Ciel nod, he let out a relieved with and pulled the boy into a hug, running his fingers through his hair.

Ciel found comfort in the demons touch as he hugged, allowing the elder to pick him and carry him back home. "Please don't let anyone take me away," Ciel said in a soft voice, resting his head against Sebastian's chest. "Don't worry, I'd never allow anyone to steal you away, my precious little one," Sebastian said as he flew up to the cave entrance and carried him inside, gently laying him down in the nest, only to feel Ciel clinging to him.

"It's okay Ciel, I'm just going to the human world to find some souls of good quality. I'll be back in a couple minutes and if any Angels come, just go deeper into the cavern and let the ravens take care of them. I taught you how to navigate the paths in these mountains so you shouldn't get lost," Ciel nodded and Sebastian smiled, putting a hand on the boys head as he walked to the entrance, taking one last glance at Ciel before flying off with a single wing beat.

Ciel watched as Sebastian flew off, a few stray feathers floating to the ground. The multi-color eyed boy cautiously approached the entrance, looking around for any signs of Angels and picked up one of the black feathers and carried it inside, holding it close as he climbed in the nest, letting himself be comforted by the familiar scent that surrounded him.

The archangel had flown back to heaven holding his broken wrist, quickly running over to an angel of higher ranking, a man with short navy blue hair and chocolate brown eyes. "Sir, I have some important information I need to report on," he said in a frantic voice. "What is it? The brown eyed angel demanded, his voice cold and strict.

"The report we got from that girl was true. It appears there's a young angel in hell, but when I tried to bring him back, a raven demon stopped me and demanded that I released him. I tried to defend myself, but ended up breaking my wrist and retreating," the brown eyed male nodded as he listened to the report,"interesting, keeping going."

"Yes sir. As I got a good distance away, I noticed the angel had found comfort in the demon and I believe he may have been raised by that creature by how corrupted his wings looked," the archangel explained. "Okay, bring more warriors with you and bring that child here at once, I must see this for myself."

The archangel saluted and walked off to do as he was ordered, leaving the brown eyed angel to sit and wait for the angels he just sent to hell to come back with the young angel that had been reported.

Ciel was fast asleep until something woke him. The sound of wing beats? Curious to see if Sebastian was back, Ciel stood with a yawn and peeked outside for his eyes to widen when he saw that it was a group of angels, four to be precise. Fear coursed through the child's body as he did the only thing I my he could think of and ran deeper into the cave, dropping down to all fours so he could squeeze through small tunnels, hiding in the dark as he heard footsteps.

Ciel could hear the angels footsteps get closer as he backed deeper into the small tunnel when he saw footsteps walk past and heard unfamiliar voices. He instinctively continued following the narrow tunnel further into the cave so they wouldn't find him, even if the did try to follow him. These tunnels were pitch black and only demons could navigate them, but Sebastian taught him how to navigate them at a young age.

He remembered playing in this maze of tunnels, climbing up and down until he would find a cave where he could rest, until Sebastian came looking for him. He could hear the Angels begin to search through the tunnels, talking about which path they should take as Ciel silently laughed, take paths that only he could fit through thanks to his small size.

His travel was cut short when he heard a monster like screech come from one of the tunnels. It was obvious that it was the creature that dug these tunnels. Ciel had only seen it once when he was curious and found out that it was a long worm like creature with razor sharp teeth. It was pretty harmless, unless it was threatened.

Ciel laughed when he heard screams and another screech, probably meaning those Angels tried to attack it. Ciel began climbing out of the tunnels, knowing the angels were chased out and Sebastian should've been back by now. He peeked out of the tunnel and saw only two of the angels were their, both badly beaten. The third must've gotten eaten.

The two angel panted heavily as they stumbled to the entrance to be met with a very angry raven demon, holding two souls in one hand, while his tail was wrapped around what appeared to be human meat and organs. Sebastian growled at the two angels and cracked his knuckles, but his expression turned into a smirk as he realized that both angels were both badly beaten.

"You tried to go through the tunnels didn't you? Usually no one survives trying to fight that creature," Sebastian said with a laugh. "We demand that you release the angel you're keeping," one of the archangels said weakly. "Hah, I thought I told you damn angels that I'd leave your asses alive if you didn't demand that. Unless you want to be feed to my pets, I suggest leaving," Sebastian growled as he wrapped a hand around one of their throats, crushing his windpipe until he was clawing at his hand, gasping for breath.

The archangels body went limp and Sebastian dropped the unconscious body before the other angels feet. "Both you need to leave, now," Sebastian demanded, his eyes glowing an ominous crimson as the angel picked up his partner and flew off with what little strength he had to go find a healer.

"Sebastian!"

The raven demon smiled when he heard Ciel's voice and saw him run toward him, unharmed. "I'm glad you're okay," Sebastian said, putting a hand on the boys head as he set the organs on the floor, shaking the excess blood off his tail as he swallowed one of the souls he held and released the other, watching as it turned into an orb and floated in place. Ciel smiled at the sight of the bleeding organs and began picking through them until he found what he was looking for. The heart.

The fact that the organ was still beating made it even better, it meant the blood would still be warm when he bit into it. "Sebastian, the heart is still beating," Ciel said excitedly. The elder looked to the organ in the child's hand and said,"oh, that's rare, but that human was putting up quite a fight."

Ciel bit into the still beat organ, loving the taste that filled his mouth. The blue haired boy continued eating the organs that sat in front of him until his mouth and hands were drenched in blood. Sebastian sighed and pulled the boy into his lap, licking the blood off his hands so he wouldn't smell like death, nor would dried blood be stuck to his skin.

"Sebastian, stop it, I'm not a infant anymore, you don't need to keep doing this," Ciel whined as the demon licked the last bit of blood from his cheek. "If you didn't like it, why did you let me continue?" Sebastian asked with a smirk. "We-Well, um I...I..." "Hehe, you're still cute as ever," The red eyed male said as he kissed the boys head, chuckling at the blush that appeared on his cheeks, and draped a wing over his shoulder, pulling him close.

Sebastian ran his fingers through the boys hair as he watched his slowly drift off to sleep. He looked to outside, glaring at the angels side of the border. If those Angels wanted what belonged to him, they'd have to kill him in cold blood.

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 **A/N: Well everyone, that was the next chapter of the story. If any of you are wondering about Sebastian and Ciel's relationship it's going to start out one-sided because Ciel thinks of Sebastian as a parent, but as the story goes on, he'll gradually find a more romantic feel to it. Anyways, sorry about the ending, I was going to make it better but I lost my train of thought and it just ruined it. Well that's all I had to say and I'll see you all in the next chapter, Ciao.**


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